[ARM] 3830/1: iop3xx: board support file cleanup

Revamp the iop3xx board support: move the support code for each iop
board type into its own file, start using platform serial and platform
physmap flash devices, switch to a per-board time tick rate, and get
rid of the ARCH_EP80219 and STEPD config options by doing the relevant
checks at run time.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>